# Safety, efficacy, OCT-assessed vascular healing and angiographic outcomes of polymer-free versus biodegradable-polymer drug-eluting stents in patients undergoing percutaneous coronary intervention: a systematic review and meta-analysis

## TL;DR

This study compares two types of drug-eluting stents and finds that polymer-free stents have higher revascularization rates but similar safety outcomes.

## Contribution

A systematic review and meta-analysis comparing polymer-free and biodegradable-polymer drug-eluting stents in coronary interventions.

## Key findings

- PF–DES showed higher target lesion revascularization rates at 12 and 24 months compared to BP–DES.
- PF–DES exhibited greater late lumen loss at 6–8 months but comparable minimal lumen diameter.
- OCT findings showed no significant differences in neointimal thickness but heterogenous results for malapposed struts.

## Abstract

Biodegradable polymer (BP) and polymer-free (PF) drug eluting stents were designed to reduce late adverse events linked to durable-polymer coatings. However, concerns remain regarding the efficacy of PF–DES particularly due to variations in drug-release mechanisms.

RCTs comparing PF–DES and BP–DES in patients undergoing percutaneous coronary interventions were included. Primary endpoints were Target lesion revascularization (TLR), Target vessel revascularization (TVR), definite stent thrombosis, Cardiac death (CD), angiographic outcomes and optical coherence tomography (OCT) findings. Risk of bias was assessed using Cochrane’s ROB 2.0 and meta-analysis performed using RevMan 5.4.

Ten RCTs including 9020 patients (4043 PF–DES; 4977 BP–DES) were included. At 12 months, PF–DES showed a significantly higher TLR rate (2.08% vs. 1.36%; RR 1.55, 95% CI 1.087–2.21; P = 0.02), persisting at 24 months (RR = 2.01, 95% CI 1.46–2.77, P < 0.0001). At 1–3 months, OCT-derived analyses demonstrated no statistically significant differences in uncovered struts or neointimal thickness between stent types, while findings related to malapposed struts were heterogenous and dependant on sensitivity analyses.

Angiographically, PF–DES showed greater in-stent late lumen loss at 6–8 months ([MD]: 0.24 mm, 95% CI 0.17–0.30, P < 0.00001), whereas minimal lumen diameter was comparable.

However, no significant differences were found in target vessel revascularization (TVR), stent thrombosis, myocardial infarction, or mortality at 1- or 2-year follow-up.

PF–DES were associated with comparable safety to BP–DES; however, it exhibited higher rates of target lesion revascularization and greater late lumen loss were observed. OCT-derived findings were heterogenous and should be interpreted cautiously. Further RCTs with standardized imaging protocols and longer follow-up are warranted.